Description:

Objective:

The objectives of the proposed research are to: (1) delineate the indoor concentration of ROS in different types of buildings and compare it to the outdoor concentration of ROS; (2) determine the factors that influence indoor and outdoor concentrations of ROS; and (3) assess the health effects of ROS.

Approach:

The study will characterize the concentration of particulate ROS in several types of buildings by collecting PM2.5 from residences, institutional buildings and retail stores. A fluorogenic probe will be used to measure the concentration of ROS on the samples of PM2.5. The indoor concentration of particulate ROS will be compared with the outdoor concentration of particulate ROS. A mechanistic approach will be used to assess the influence of specific building and other factors (including building age, total volatile organic compound concentration, distance from a major roadway, windows open or shut, indoor and outdoor concentrations of PM2.5, outdoor ozone concentration, and indoor and outdoor temperature) on the concentration of ROS. Furthermore, the seasonal variation in the outdoor concentration of particulate ROS also will be assessed. The accuracy of all ROS measurements will be verified by conducting several experiments, including investigating the rate of decay of particulate ROS on sampled filters. In addition, the potential health effects of reactions that produce ROS will be assessed with an in vitro exposure model. Human lung epithelial cells will be exposed to ROS generated by a mixture of ozone and a model terpene, and the inflammatory proteins expressed by the lung cells in response to this exposure will be assessed. In this way, the research will delineate the concentration of particulate ROS in indoor and outdoor environments, determine the factors that influence the concentration of particulate ROS and assess the potential health effects of ROS.

Expected Results:

This research will expand the understanding of the importance and potential health effects of ROS. It will provide insight into the indoor-tooutdoor ratio of particulate ROS and is one of the first studies to assess ROS in indoor environments, especially houses, where people spend the majority of their time. Sampling conducted to date in residential, institutional and retail buildings indicates that the indoor concentration of particulate ROS can be, on average, 80 percent greater than the outdoor concentration of particulate ROS. This can have important implications on the extent of exposure to particulate ROS. It is anticipated that the results from this study will help delineate the factors that influence indoor concentration of ROS; these results will be integrated to help determine the most effective strategy to limit exposure to ROS. Outdoor sampling conducted over several months already has shown that ROS is influenced partially by the ambient temperature. Furthermore, preliminary results from experiments already conducted at the National Institute for Occupational Safety and Health with an in vitro exposure model indicate that exposure to ozone-initiated reactions that produce ROS leads to greater inflammation in human lung epithelial cells than exposure to ozone alone. This research highlights the need to better understand the extent of exposure to this class of pollutants.

Potential to Further Environmental/Human Health Protection

Although there has been significant focus on the health effects of ozone, the relative health effects of products from ozone-initiated reactions have not received as much attention. This research will help determine the extent of exposure to products from ozone-initiated reactions as well as their potential health effects. Furthermore, the results from different components of this research will be integrated to elucidate the most effective strategy to limit exposure to ROS.

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.